The aim of this study was to assess the force degradation of different types of elastomeric orthodontic chains subjected to tensile strength during different periods of time in artificial saliva at 37°C. A total of 312 elastomeric chains were evaluated. Six different types were studied: transparent extra‐straight (TXS), transparent straight (TS), transparent wide (TW), gray extra‐straight (GXS), gray straight (GS), and gray wide (GW) chains. Forty‐eight different groups were made, six as controls. The remaining 42 groups were subjected to tension until initial length doubled in varying periods of time (1, 3, 24, 96, 160, 360, and 720 h). The tensile strength was measured using an Instron machine. Our results showed that most of the loss in strength occurred during the first hour (50.72% for TXS chains, 30.80% for TS chains, 64.51% for TW chains, 41.57% for GXS chains, 29.99% for GS chains, and 25.32% for GW chains) and reached a maximum peak at 4 days. This was followed by a recovery during the remainder of the experimental period. Gray chains demonstrated less force decay when compared with transparent chains. Our conclusions were that loss of strength depends on time, thickness of the elastic chains, and distance between the links. These findings might serve as a practical guideline for the clinician.

In this paper, we present a brief exposition of the history of the secured credit card, beginning with its origins in California in the 1970s. We present a series of stylized facts based on a December 2015 cross section of the secured card market. We find that most secured cards require an annual fee, tend not to have promotional offers or rewards, and often have higher purchase annual percentage rates than their unsecured counterparts. We also find that the percentage of secured card accounts in a delinquency status is more than double that of unsecured cards and that far fewer secured cards are inactive compared with unsecured cards. In addition, the annual income of secured card consumers is about 43 percent lower than unsecured card consumers. Last, we examine how the credit scores of consumers opening a secured card account change during the first two years of account history. We find that keeping a secured card account open is correlated with improved creditworthiness, while closing an account, either in good standing or in default, is correlated with significantly reduced creditworthiness.

This paper uses tradeline-level credit card data to examine initial credit limits and early credit limit increases before and after the Great Recession and implementation of the Credit Card Accountability, Responsibility, and Disclosure Act of 2009 (the CARD Act). I compare two vintages of credit card accounts, those opened in 2005 and 2011; I also follow each vintage for more than two years after the account opening. In general, I find that significantly less credit was extended to approved credit card applicants in 2011 than in 2005. Accounts in the 2011 vintage started out with lower initial credit limits, received fewer limit increases, and received a smaller increase amount in dollar terms. These changes were most pronounced among the riskiest 25 percent of accounts opened in 2011. For this segment of the market, the median initial credit limit fell 66.7 percent to $500, and the median limit increase amount fell by at least 25 percent at each observation point. At the same time, limit increases occurred more often and sooner for this group, perhaps in recognition of the very low starting limits.

Tender mixes are defined as asphalt concrete (AC) mixes that shove excessively under steel wheel rollers, do not densify, and remain soft for extended periods of time after construction. Improper aggregate gradation, very little aggregate angularity, low filler content, high aggregate moisture content, and improper compaction procedures are the principal causes of tender mixes. However, under critical mix conditions the type of asphalt used can also determine the tenderness, or conversely the toughness, of an AC mix. Laboratory tests are examined to establish those physical properties of the asphalt that influence the toughness of a mix. These properties are related to the pavement toughness as measured in a full-scale paving laboratory in which actual paving construction practices are simulated. Pavement toughness is established at 100 F and at a uniform mix density. The penetration at 77 F and viscosities at 100, 140, and 275 F (or any combination of these properties) of the original asphalt show very poor to fair correlations with pavement toughness. An excellent correlation is obtained between pavement toughness and the viscosity at 100 F of asphalts recovered from test pavements. The viscosity at 140 F of aspalts exposed in the rolling thin film oven (RTFO) also relates well to pavement toughness. An excellent correlation for all asphalts tested results when the rolling thin fim (RTF) viscosity of the asphalt and toughness of the mix are compared at the same test temperature of 100 F. The viscosity at 140 F of an RTF residue is proposed as a practical method for grading setting qualities of paving asphalts. This viscosity can be determined rapidly and routinely in the laboratory.

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